RE: [Discuss-gnuradio] Decimation scheme

[Bob McGwier]

Sebastian:

http://users.snip.net/~donadio/cic.pdf

contains more than you ever wanted to know about CIC filters in great detail
including how to calculate the transfer function.

Bob


ARRL SDR Working Group Chair
Member: ARRL, AMSAT, AMSAT-DL, TAPR, Packrats,
NJQRP, QRP ARCI, QCWA, FRC.
"Trample the slow ....  Hurdle the dead"


-----Original Message-----
From: address@hidden
[mailto:address@hidden On Behalf Of
Brian Padalino
Sent: Wednesday, July 16, 2008 3:12 PM
To: Sebastiaan Heunis
Cc: address@hidden
Subject: Re: [Discuss-gnuradio] Decimation scheme

On Wed, Jul 16, 2008 at 2:46 PM, Sebastiaan Heunis <address@hidden>
wrote:
> Hi
>
> Can anyone please help me with some information on the CIC filters in
> the USRP?  I need to know how many CIC stages there are, what the
> cutoff frequency and out of band rejection is and how the decimation
> is performed after filtering.  Which .v files should I have a look at?

The decimating CIC filter implementation can be found here:

 
http://gnuradio.org/trac/browser/gnuradio/trunk/usrp/fpga/sdr_lib/cic_decim.
v

It's a 4-stage CIC filter.  Decimation is somewhat inherent within the
process, so I don't understand that question.  Sorry.

Good luck.

Brian


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